Using energy demand management to increase uptake of wind power
Published 11:50, 18 April 08
Image by Mancio7B9 via FlickrI read an article this morning on TechnologyReview.com which was makes the case for using more accurate weather forecasting to prevent blackouts and reduce pollution. Nothing wrong with this idea per se, but forecasting alone won't go nearly far enough to solve instability problems introduced by increasing the amount of wind energy into a grid.
Ireland's National Control Centre already makes extensive use of weather information and currently we generate, on average 6.5% of our power requirements from wind. However at 3am on a summer's morning, with a 40mph wind blowing over the country, that can rise to almost 50% (demand at that time is typically 1.8GW and supply from the 40mph wind is around 0.9GW).
The Irish government has committed to raising the amount of power generated by wind to an average of 33% by 2025. When that happens on a similar summer's morning at 3am with the increased number of wind farms deployed, lets say demand across the country has doubled to 3.6GW the supply from wind will be 6.3GW - that's 2.7GW excess over demand! No amount of forecasting, however accurate will fix that.
And no, you can't shut down the wind farms because if there were any possibility of that, the banks would run a mile from financing them and you would never achieve your 33%.
Conversely the current peak demand in Ireland comes in around 5GW and if this grows to 10GW by 2025 this means Ireland could potentially need to invest in building installed generation capacity of 10GW from non-wind sources to cope with calm days.
So what do you do? Well, if you can't control the supply, you have to control the demand. To do that you use Energy Demand Management (EDM). In other words you let the market set the price for electricity in real-time based on actual supply and demand. You publish the pricing in real-time using web services and demand will react accordingly.
When there is a shortage of electricity (on calm winter evenings when everyone has their Christmas lights on, for example) electricity pricing will spike. At this time, organisations with diesel generators or gas turbines, if notified of the increase in price will switch to their own generation if it is cheaper. This will take their demand out of the equation and there is the possibility of their selling any excess generation back into the grid
helping to further alleviate the problem - a win-win.
In a domestic situation, smart meters capable of taking pricing information from the grid and controlling devices around the house accordingly, may decide to increase the temperature setting on the fridge by a degree or two, reduce the temperature on the central heating or immersion a degree or two, pause dishwashers or dryers until electricity is cheaper - all easily configurable by the house owner obviously.
In the situation where there is an excess of supply over demand, electricity pricing will go negative. In other words, in cases of a significant oversupply of energy (remember the 2.7GW example above?) we will be paid to consume power! Refrigeration plants can drop the settings on their thermostats, ice bank air conditioners can start cranking out the ice, swimming pools can turn up the heat and it may even be economical to start making hydrogen to store (and burn later as a clean energy source when the price increases again).
And, in the domestic situation, smart appliances can start up, thermostats can adjust to suck in power and plug-in hybrid vehicles can start to act as a national distributed energy store.
In 2007 the cost of electricity generation in Ireland varied from 6c per kWh to over 1€ per kWh. This variation in costs was never passed on to the consumer. Had it been I suspect we would have seen remarkably different patterns of usage.
If supply and demand are brought more into synch using demand side management, the instabilities normally associated with increased wind energy on the grid automatically become significantly more manageable thereby allowing for a far higher penetration of wind energy into the market.